What do you base your RDAs on?

I'm come from the planet where we have this idea that blood work is a manifestation of your diet, not a manifestation of your health. So high levels of something or low levels of something doesn't really mean you're systematically killing yourself (or adding extra days to your life) in the long run but rather it's just a reflection of your diet and the mirror is your blood.

Sure there are standards and RDAs, but how accurate are those? Our diet is completely different from most, so I have to wonder what groups of people those RDAs are based off of? What was the standard of that standard?

I'm wondering because I notice that a lot of people who are Paleo do supplement with vitamins and take fish oil, etc., what do you base the choices of your doesages on and why do you take the vitamins you do? Obviously the food chain was higher quality a couple thousand years ago but aside from that e.g. not everybody lived by a water source teaming with salmon or shellfish.

For the most part, I presume that a broad diet consisting of only whole foods is sufficient to meet RDAs. When I've put through a typical day in a nutrient calculator I blow the RDAs out of the water pretty much.

I am careful about items like vitamin D (and to a lesser extent beta-carotene due to turning skin orange) due to their possible downsides. If I am supplementing something, like Vitamin D (something like 95% of people in my area are deficient when it gets surveyed, high latitude low altitude) then I stay well away from overdose levels (a fair number of people seem to use OD levels as a starting point.....).